Process for treating fruit juice



/ Patented Nov. 53%

' UNITED STATES PATENT OFFICE 2,059,789 rnocnss ron TREATING FRUIT JUICE George Grindrod, Oconomowoc, Wis., assignor to GrindrodProcess Corporation, Dover, Del., a

corporation of Delaware No Drawing. Application February '14, 1935,

Serial No. 6.485

Claims. (Cl. 99-155) This invention pertains to a process for treating fruit juice and relates more particularly to a process for preserving fruit juice.

N It is an object of the invention to provide a, practical commercially operable process for pre serving fruit juice, particularly orange'juice, by

Another object is to provide a canned juice, particularly orange juice, which will keep appreciable lengths of time without deterioration and which has retained practically unchanged its original flavor and color.

Other objects will be in part obvious and in part pointed out hereinafter.

This application is a continuation in part of my copending application Serial No.- 393,113 entitled Fruit juice products.

The invention comprises the several steps and sequence of steps, the selection of substances, the maintaining, of desired proportions, conditions, etc. as exemplified in the embodiment hereinafter described and in the claims.

Orange juice and many other fruit juices after extraction from the fruit are susceptible to oxielation, bacteria and other influences which change the chemical and physical structure thereby changing the flavor, aroma, and color."

Unless preserved, orange juice cannot be kept 5 any apreciable length of time after extraction without undergoing these objectionable changes. Many methods have beentried in an effort to find one which would preserve the juice in its natural condition as extracted from the fruit but 40 with none of these methods (without the aid of refrigeration) has it been possible to preserve thejuice without materially changing its taste.

One of the methods tried, the customary prolonged heat treatment at 2140-150" F. of canned or uncanned juice applied to destroy bacteria,.

not only destroys the bacteria-but also changes theflavor and aroma, so as to render the juice unpalatable to many. Further, this treatment evidently renders the juice unstable for upon standing'any appreciable length of time after treatm'cnt it becomes acrid, indicating a spontaneous chemical change probably prompted by the heat treatment. Thus the heat treatment tried caused thermo-chemical change in the fruit juice as well as sterilization. Another method, sterilization by trate the invention the kineticj energy is profiltration, is unsatisfactory because it removes color, taste, and body, and is generally impractical with a pulp filled juice such as orange juice.

Another method wherein ,the juice is not sterilized but is preserved by adding a substance such' 5 as sugar which inhibits bacterial growth changes the natural flavor.

Thus, all these processes producev changes, in the fruit juice which make it taste quite different from that of the natural juice. It is another 10 object of this invention to overcome these difficulties an to provide a process which preserves orange juice and other fruit juices without causing appreciable change in flavor and aroma, and which improves the stability.of the juice. 15 The present invention contemplates a process comprising subjecting orange juice maintained at certain conditions of temperature and pressure to the action of heat and kinetic energy for a period of time sufficient to destroy harmful bacteria present but insufiicient to cause objectional thermo-chemical changesin the fruit juice suchas would cause an appreciable change in the-taste. In the embodiment chosen to illusvided by steam jets having apreciable velocity such as disclosed in my United States Patent 1,797,769. I 5 Orange juice is extracted (preferably in. a vacuum or in the presence of an inert gas since 30 the juice is extremely sensitive to oxidation) and then the extracted juice is first preferably pre-heated in the absence of oxygen to a temperature between 120-130 F., in a suitable heat exchange apparatus in which localizeh over-heat-, ing, is avoided. "This may be accomplished in a suitable continuous flow heater with rapid movement of the juice theretlirough. For this step and throughout the process acid resistant apparatus is considered preferable. 13y pre-heating the 40 juice in this way the subsequent steam jet treatment does not cause as much dilution by,condensation as would otherwise occur and the time required for the treatment is reduced. The juice may be heated to these temperatures for a reason- 45 ably short period of time without causing notice.-. able thermo-chemical decomposition of the juice. The heated juice is next preferably subjected -to a vacuum or low pressure, about 3 pounds per square inch absolute, wherein undesirabledissolved gases suchv as oxygenare released. An atmosphere free from oxygen such as dry steam has been found to be suitable to accomplish this step of the process. This step may be eliminated where the juice is free from oxygen or under certain other conditions of operation.

'I 'he gas-free pre-heated juice is now subjected to heat and kinetic energy by which the temper square inch absolute which is maintained. In the present embodiment this is accomplished by introducing into thevliquid body of the juice steam jets having a high velocity, for example, at or above 1400 feet per second. The steam jets may be similar to those described in. the abovementioned patent. The 3 pound'absolute pressure may be maintained by drawing oif'the steam perature of the juice is raised from the pre-heated temperature to that corresponding to 3 pounds and water vapor'by a suitable mechanism such as, for example, a waterjet ejector, a steam vacuum pump, or the like. This step of the process is started and preferably carried out in an enclosed spacefree. from oxygen and other gases deleterious to the juice by' first flushing with steam the space in which the process is being be large enough to allow the steamjets effectively to impart their kinetic energy to the orange juice and should be designed so that the steam in.

passing from the enclosure does not carry the orange juice with it. When working with a batch process it has been demonstrated that a contain 1 er 20 per cent filled with orange juice gives satisfactory results.

Further experiments have demonstrated that? the" steam jets should be dry and to, insure the 'dryness should have some superheat; Thus, it

has been found practical to start with steam at about pounds per squareinch gauge,( adiabatically expand it down to about 5 pounds per square inch gauge and then pass it through either orifices or adiabaticnozzles to form it into jets which contact directly with the orange juice.

-It has been found-that, when working with a batch process and with steam jets having a velocity of approximately 1400 feet per'second the steam treatment raises the temperature almost instantly to that which corresponds'to' the 3 pounds absolute pressure (about-HO E), and

that by continuing this kinetic energy and heat treatment for a period of one to two minutes the juice is sterilized. The juice is then immediately thermo-chemical decomposition R). My results have demonstrated that the destruction of the bacteria'harmful to the juice is accelerated by my process to a degree much out of proportion to thermo-chemical changes af fecting other constituents of thejuice so that the bacteria are devitalized before objectional thermo-chemical'changes take place. Further the juice is stable and has been found to keep without deterioration for periods of time much longer than juice sterilized or pasteurized by the slow heat treatment processes.

The immediate cooling of the juice may be accomplished by running the sterile juice into a vacuum containing a pressure lower than 3 pounds per square inch absolute whereby rapid boiling and consequent evaporation of the water of the juice immediately lowers the temperature. Further cooling of the product before bottling may be accomplished by suitable heat exchange apparatus. The two stage cooling has been found desirable to accomplish the first immediate coolconcentration is correct. If it is desired to change I demonstrated" ing very rapidly so that the product could be lowered below the chemical. change may change, has an opportunity to take place. The

product is nowjreadytfor bottling providing the the concentration by reducingtit, of course heat may be supplied while" the product is in the cooling vacuum chamber to remove as much water-as is desired.

Inasmuch as ,the more important flavor giving constituents, of orange juice are considered to have a low vapor pressure, the steam jet treatment should not distill these off andmy experiments have indicated that the steam treatment does not distill off anamount of these constituents sufficient-to cause any appreciable change in the taste of the juice.

'1 The results obtained by my experiments have indicated that exact conditions'of temperature and pressure as well as conditions of atmosphere and periods. of time should be closely adhered to inorder to hbtain maximum favorable results, For example by raising the temperature to F. the time required for obtaining sterility is generally materially reduced, and in. some instances.

temperature at which thermotake place before suchis-reduced the quality of the product obtained is, A

temperature. Also with regard tothe temperaturebf the "steam employed, experiments have hat if the temperature of the steam jets is much above 230 F., a less perfect product is obtained. The number of degrees of likely to be inferior to that processed at alower superheat is hot importantbutby-having 5 to 10 of superheat, a suflicient factor of safety is proyided for the assurance of dry steam. Wet steam while it may be used is not as satisfactory as dry steam because of-its tendency to condense and so dilute the product and also because of its slower speed.

. It has been found that the process is equally adaptable to orange juice. that has been diluted,

concentrated or left as it is extracted, whereas concentrated juice will withstand practically no heating by the usual heat treatment. Usually, however the juice is concentrated for bottling after the heat treatment and as above described this may be carried out inthe vacuum cooler used for the. first cooling step.

With the process described it is possible to preserve fruit juice and particularly orange juice without appreciably changing the flavor, aroma or. color, of the juice, the juice being preserved so that it is stable for an appreciable length of time. Ashas been pointed out, although various heat treatments have been proposed in the past, none of them have succeeded in sterilizing the juice without causing thermo-chemical changes to take place either at the time of the heating or spontaneously thereafter. With the temperature limits and steam or kinetic energy treatment described the heat treatment of the present invention sterilizes the juice before any thermal decomposition takes place and-without causing thermo-chemical changes which may later spontaneously cause be interpreted as illustrative and not in a limitsteam jets not over 230 F. while maintaining the I 3 pounds per square inch pressure absolute to heat the juice to a temperature corresponding to the 3 pounds per square inch absolute pressure and continuing the heat treatment for approximately two minutes until sterility is obtained but before appreciable thermo-chemical change is 'produced, and then instantaneously cooling the juice to a temperature below that necessary to produce thermo-chemical change by subjecting the juice to a low vacuum:

2. A process for preserving orange juice comprising the steps of pre-heating the juice out of the pressure of air to a temperature below that necessary to produce thermo-chemical change, subjecting the juice to the heat and kinetic energy of high velocity steam jets not over 230. F.

to raise the temperature of the juice approximately instantaneously to between 140-155 F.,

and continuing the heat treatment while main-' taining said temperature until the product is sterilized but stopping before appreciable thermo-chemical change is produced, 'and'then approximately instantaneously cooling the juice to a temperature below that necessary to produce while maintaining the pressure surrounding the thermo-chem'ical change by subjecting the juice to a vacuum sufllcient to cause it to boil.

3. A process for preserving orange juice comprising the steps of rapidly pre-heating the juice out of the presence of air to a temperature below that necessaryto cause thermo-chemical change, subjecting the juice to the heat and kinetic energy of high velocity super-heated steam jets juice at approximately 3 to 4 pounds per square inch absolute to heat the juice to a temperature corresponding to the pressure and continuing the heat treatment for approximately two minutes until sterility is obtained but stopping before appreciable thermo-chemical change is produced and then substantially instantaneously cooling the juice to a temperature below that necessary to produce thermo-chemical change.

preserving orange juice com- 4. A process for preserving orange juice comprising the steps of rapidly pre-heating the juice out of the presence of air to a temperature below that necessary to cause thermo-chemical change, subjecting the juice to the heat and kinetic energy of high velocity super-heated steam jets while maintainingthe pressure above the juice at approximately-3 to epounds per square inch absolute; to heat rapidly the juice to a temperature corresponding to the pressure and continuing the heat treatment until sterility is obtained but stopping before appreciablethermo-chemical change is produced.

5. Aprocessfor preserving orange juice comprising the steps of rapidly preheating the juice out of the presence of air to a temperature below that necessary to cause thermo-chemical change, subjecting the juice to the heat and kinetic energy of high velocity dry steam jets while maintaining the pressure above the juice at approximately Bto 4 pounds per square inch absolute to heat rapidly the juice to a temperature corre-. sponding to the pressure and continuing the heat treatment until sterility is' obtained but stopping before appreciable thermo-chemical change is produced.

6. A process for preserving orange juice comprising the steps of subjecting the juice to a low pressure vacuum toremov dissolved ases therefrom, subjecting the juice to the heat and kineticenergy oi dry high velocity steam jets free from air while maintaining the pressure surrounding the juice at approximately 3 pounds per square inch" absolute and continuing the treat.- ment forapproximately two minutes until sterility is obtained but stopping before appreciable ther-- mo-chemical change is produced and then instane taneously cooling the liquid juice to a temperature below that sufiicient tocause thermo-chemical change.

7. A process for preserving new comprising the steps of rapidly pre-heating the juice out of the presence of air to a temperature below that necessary to cause thermo-chemical change, subjecting the juice to the heat and kinetic energy of high velocity dry steam jets free from oxygen and not over 230 F. while maintaining the pressure above the juice suflicient to maintain it at between and F. and continuing the treatment until sterility is obtained but stopping it before appreciable therrno-chemical change is produced and then instantaneously cooling the juice to a temperature below that necessary to produce thermo-chemical change.

GEORGE GRINDROD. 

